The characterization of sunburn basalts and their magnetic and petrographic properties

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985831%3A_____%2F18%3A00500530" target="_blank" >RIV/67985831:_____/18:00500530 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/67985891:_____/18:00500530

Výsledek na webu

<a href="http://dx.doi.org/10.3190/jgeosci.274" target="_blank" >http://dx.doi.org/10.3190/jgeosci.274</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.3190/jgeosci.274" target="_blank" >10.3190/jgeosci.274</a>

Jazyk výsledku

angličtina

Název v původním jazyce

The characterization of sunburn basalts and their magnetic and petrographic properties

Popis výsledku v původním jazyce

Sunburn texture, a white-grey mottling of dark grey basalts, is frequently found in outcrops around the world. The sunburn basalt is more fractured and less resistant than the fresh one, and so its identification is of interest in all types of basalt quarries. Three localities were chosen with different types and shapes of volcanic bodies in the Lausitz Volcanic field in the border area of the Czech Republic and Germany (Borska Skalka, Mittelherwigsdorf, Wittgendorf) in order to characterize sunburn lavas and study the petrographic and magnetic changes between fresh massive and sunburn basalts. The sunburn basalts have cracked, disrupted outcrop surfaces where white-grey spots are observed. As seen in thin section, the spots contain mainly analcite, the mineral that is responsible for the sunburn effect. The appearance of analcite is indicated by the enhanced amount of Al and Na. The whole rock is affected by many cracks that are filled with limonite. Limonite also infiltrates the sunburn spots, which are rich in microcracks. In the field were measured thirteen profiles perpendicular to the volcanic bodies in order to describe the magnetic properties in situ (magnetic field intensity, inclination and declination values). The intensity of magnetic field and its azimuth change with the distance from the rock. A major change occurs c. 130 cm away from the wall, which implies that the major cause is at some distance. The changes in magnetic inclination were negligible with the exception of the Borska Skalka site, where standard deviation of the magnetic field was 29.3 mu T, and the standard deviation of the azimuth 78.7 degrees for the sunburn part. In the laboratory were measured natural magnetic resistivity (NMR) and isothermal remanent magnetization (IRM). The calculated REM (remanent magnetization) parameter averaged 2.0 % for the sunburn parts and 0.8 % for the massive basalt. The sunburn basalts are affected mainly by weathering and hydration that causes changes in petrophysical and magnetic properties. The most prominent changes in all the variables could be seen at Borska Skalka, whose top is exposed to lightnings. Because of the increased conductivity, the sunburn parts become preferred lightning paths and the initial magnetic properties of the basalt can be overprinted by the electrical activity.n

Název v anglickém jazyce

The characterization of sunburn basalts and their magnetic and petrographic properties

Popis výsledku anglicky

Sunburn texture, a white-grey mottling of dark grey basalts, is frequently found in outcrops around the world. The sunburn basalt is more fractured and less resistant than the fresh one, and so its identification is of interest in all types of basalt quarries. Three localities were chosen with different types and shapes of volcanic bodies in the Lausitz Volcanic field in the border area of the Czech Republic and Germany (Borska Skalka, Mittelherwigsdorf, Wittgendorf) in order to characterize sunburn lavas and study the petrographic and magnetic changes between fresh massive and sunburn basalts. The sunburn basalts have cracked, disrupted outcrop surfaces where white-grey spots are observed. As seen in thin section, the spots contain mainly analcite, the mineral that is responsible for the sunburn effect. The appearance of analcite is indicated by the enhanced amount of Al and Na. The whole rock is affected by many cracks that are filled with limonite. Limonite also infiltrates the sunburn spots, which are rich in microcracks. In the field were measured thirteen profiles perpendicular to the volcanic bodies in order to describe the magnetic properties in situ (magnetic field intensity, inclination and declination values). The intensity of magnetic field and its azimuth change with the distance from the rock. A major change occurs c. 130 cm away from the wall, which implies that the major cause is at some distance. The changes in magnetic inclination were negligible with the exception of the Borska Skalka site, where standard deviation of the magnetic field was 29.3 mu T, and the standard deviation of the azimuth 78.7 degrees for the sunburn part. In the laboratory were measured natural magnetic resistivity (NMR) and isothermal remanent magnetization (IRM). The calculated REM (remanent magnetization) parameter averaged 2.0 % for the sunburn parts and 0.8 % for the massive basalt. The sunburn basalts are affected mainly by weathering and hydration that causes changes in petrophysical and magnetic properties. The most prominent changes in all the variables could be seen at Borska Skalka, whose top is exposed to lightnings. Because of the increased conductivity, the sunburn parts become preferred lightning paths and the initial magnetic properties of the basalt can be overprinted by the electrical activity.n

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10505 - Geology

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2018

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Journal of Geosciences

ISSN

1802-6222

e-ISSN

—

Svazek periodika

63

Číslo periodika v rámci svazku

4

Stát vydavatele periodika

CZ - Česká republika

Počet stran výsledku

12

Strana od-do

333-344

Kód UT WoS článku

000454518300005

EID výsledku v databázi Scopus

—